A more thorough explanation:

The Geneva Conventions and their Additional Protocols are a set of international laws that provide minimum protections, standards of humane treatment, and fundamental guarantees of respect to individuals who become victims of armed conflicts. These laws were created to protect civilians, prisoners of war, and soldiers who are otherwise rendered incapable of fighting. The first Convention was adopted in 1864 to establish the red cross emblem signifying neutral status and protection of medical services and volunteers. Other emblems were later recognized, and the Geneva Conventions of 1949 confirmed them all.

There are four Geneva Conventions and three Additional Protocols:

• Convention I: Protects wounded and infirm soldiers and medical personnel who are not taking active part in hostility against a Party.
• Convention II: Extends the protections described in the first Convention to shipwrecked soldiers and other naval forces, including special protections afforded to hospital ships.
• Convention III: Defines "Prisoner of War," and accords such prisoners proper and humane treatment as specified by the first Convention.
• Convention IV: Affords civilians the same protections from inhumane treatment and attack afforded to sick and wounded soldiers in the first Convention.
• Protocol I: Further restrictions on the treatment of "protected persons" according to the original Conventions, and clarification of the terms used in the Conventions was introduced.
• Protocol II: Further clarifies the fundamentals of "humane treatment" and specifically enumerates the rights of interned persons charged with crimes during wartime.
• Protocol III: Adds another emblem, the "red crystal," to the list of emblems used to identify neutral humanitarian aide workers.

The Geneva Conventions apply to all cases of declared war between signatory nations, all cases of armed conflict between two or more signatory nations, and even to a signatory nation if the opposing nation is not a signatory, but only if the opposing nation "accepts and applies the provisions" of the Conventions. The Conventions provide for universal jurisdiction, which means that some crimes, such as genocide, crimes against humanity, torture, and war crimes, are so exceptionally grave that they affect the fundamental interests of the international community as a whole. Every State bound by the treaties is under the legal obligation to search for and prosecute those in its territory suspected of committing such crimes, regardless of the nationality of the suspect or victim, or of the place where the act was allegedly committed.

For example, Convention III defines "Prisoner of War" and requires POWs to give only their names, ranks, and serial numbers to their captors. Nations party to the Convention may not use torture to extract information from POWs. This illustrates how the Geneva Conventions protect the rights of prisoners of war and prohibit inhumane treatment.

Another example is Common Article 3, which requires humane treatment for all persons in enemy hands, without discrimination. It specifically prohibits murder, mutilation, torture, the taking of hostages, unfair trial, and cruel, humiliating and degrading treatment. It requires that the wounded, sick and shipwrecked be collected and cared for. It grants the ICRC the right to offer its services to the parties to the conflict. It calls on the parties to the conflict to bring all or parts of the Geneva Conventions into force through "special agreements." It recognizes that the application of these rules does not affect the legal status of the parties to the conflict. This illustrates how the Geneva Conventions apply to non-international conflicts and establish fundamental rules from which no derogation is permitted.